import java.util.*;

public class T03 {

    static int opera(int c, int X, int Y) {
        if (c == 12) return 1000;
        else if (X == Y) return c;
        else {
            return Math.min(opera(c + 1, Y, X), opera(c + 1, X + Y, X - Y));
        }
    }
            
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        int Y = sc.nextInt();

        int ans = opera(0, X, Y);
        if (ans == 1000) ans = -1;
        System.out.println(ans);
    }
}